I use the EOS Remote app but you can only take single shots and bursts ie. no timer controlled shots like you can do with a remote shutter for time lapses. Surely there must be an app out there that can do this?
I think you can use the DSLR controller for Android
Though, for time lapse I would suggest magic lantern. Although it's not officially released, nor officially stable, I'm using it on mine and it's stable.
You can do timelapses from within the camera.
Bernard, I just realised your question did not specify a mobile phone app.
On the 6d though, you can wifi to your laptop and run EOS Utility and use that for a timer release. See this quick guide to use EOS Utility
If you don't have a wifi router avail, you can make an ad-hoc network to your laptop and have the 6d connect to it. The 6d DOES take longer to connect to an ad-hoc network than a router though. At least with the laptop being win7.
Alternatively if you dont' want to make an adhoc network, you can turn your phone into a wireless hotspot and connect both the laptop and the camera to it.